Telephone system



F- L. KAI-1N TELEPHONE SYSTEM FiledfNpv. 30. 1951 Dec. Y.20, 1932.

Patented Dec. 20, 1932 UNITED STATES PATENT OFFICE FREDERICK L. KAI-IN,OF CHICAGO, ILLINOIS, ASSIGNOE, BY MESNE ASSIGNMENTS, T ASSOCIATEDELECTRIC LABORATORIES, INC., 0F GECAGO,A ILLINOISpA CORPORA- TION OFDELAWARE rnnnrnonn SYSTEM Y Application led November 30, 1931. SerialNo. 577,931.

rEhe present invention relates in general to automatic telephonesystems, and its object, broadly stated, is to provide new and 1mprovedcircuit arrangement-s for the type of switches known asrotary'connectors. As to certain features of the invention, it may beconsidered as an improvement on the rotary connector shown in theapplication to'li` udolph F. Stehlik, Patent No. 1,716,986, 1ssued Junel1, 1929.

Rotary connector switches are provided for the purpose of establishing aconnection with an idle line of a. group of lines, which are all listedunder the same telephone number in the directory. Heretofore it hasb-een the practice in case of night service to assign a number to one ofthe lines in a group which is dinerent from the number assigned to theentire group for day service. The telephone number assigned for dayservice corresponds to the first line of the group, while the numberassigned for night service corresponds to some number other than that ofthe first line in the group.

In the above-mentioned Stehlik patent the connector is arranged to huntfor the first idle line in a group of lines when the numberl of thefirst line is called and if all the lines in the group are busy theconnector will come to rest on the last line of thegroup and will returnbusy tone to the callingy subscriber. The connector is so arranged thatif anyV line other than the first line in a group is called the switchwill come to rest on the called line and will switch theconnectionthrough, if the line is idle, or will give busy tone to the callingsubscriber, if the line is busy. It may be desirable in some cases tohave the first line of the group, as well as all the rest of the lines,dialled direct without the automatic rotary action to select an idleline of the group if the first line happens to be busy. rlhis result isaccomplished by the present invention.

ficcordingito the present invention a threedigit connector is providedin which' any line in a group of lines maybe called direct, or

which Jhe connector is operated to automatically'select an idle one ofthe lines in a group of lines. This is brought about by the use of twodiscriminating relays which are both operated when a certain first digitis dia-lied and prepare the connector to operate as a regular connector.l/Vhen a different predetermined first digit is dialled only one of therelays .operates and the switch is then prepared to operate as a rotaryconnector and 'will automatically select an idle line in a group oflines.

Another object of the invention is to provide a connector which willfunction as a combined regular and rotary comiector on certainlevels,'and which will function as a regular two-party line connector oran individual line connector on other levels. This is accomplished inthe present invention by using a discriminating preliminary digit, whichdetermines further operation of the connector on trunk hunting levels,and which determines the side of the line the ringing current will betransmitted over, on levels assigned for two-party service. Individuallineservice is the' same as two-party line service, except that leachsubscriber'has his individual line.

The foregoing objects and features 'together with others notspecifically mentioned at this time will be further discussed inconnection with the detailed description of the operation ut theconnector.

The accompanying drawing shows a threedigit, combined rotary, two-party,and indi,- vidual line connector, which is one of a pluralty of similarswitches which are accessible to subscribers in a telephone system overthe well-known lineswitch, associated master switch, and selectorswitches. The subscribers lineswitch, master switch, and selectorvswitch may be of the type shown in Fig. l of the Victor S. Tharpapplication, Serial No.-5l0,680, filed January 23,1931. The connector isof 'the well-known vertical and rotary type switch having its banlrycontacts arranged in horizontal rows or levels. Four wipers areprovided. The test Wiper 259 and its associated bank are only used whenthe swtich is operating as a rotary connector.

'The automatic rotation is accomplished by strapping each test contactassociated with the regular test wiper 258, with the exception of thelast one in the group, to the corresponding test contact associated withthe auX- iliary test wiper 259.

The substation A1 is one of a plurality of substations connected to agroup of lines accessible. to the connector. It is understood in thepresent case that the third level of a connector is set aside for linesof this type. The substations B1 and B2 are connected to the same lineconductors 264 and 266. The line comprising conductors 264 and 266 isone of a plurality of two-party lines accessible over the second levelof the connector.

The present invention, having been described in general, will now bedescribed in connection with the detailed description of the operationof the apparatus shown on the drawing.

Referring to the drawing, it will be assumed that a calling subscriberdesires to establish a connection with one of the lines in the groupwhich includes the line extending to station A1. When the callingsubscriber removes his receiver, his individual lineswitch operates asusual and seizes an idle trunk line leading to a selector switch. Inresponse to the operation of the'calling device, the selector switch isoperated to select an idle trunk line leading to a connector. lt will beassumed that the connector shown in the drawing is selected.

1When an idle contact set is reached (for example, the contact set fromwhich the conductors 13S-140 extend to the present connector) a batterypotential is encountered on the test contact thereof by wiper 128. rlheconductor 139 which extends to the present connector being connected tolbattery through armatures 220, 244, and 256 and their respective restingcontacts.

l/Vhen this battery potential is encountered by the test wiper 128, ofthe Tharp selector,

,the switching relay 104energizes over its upper winding and locksitself over its lower winding. The operation of the switching relay 104extends the calling subscribers line conductors through the wipers 12Tand 129, conductors 138 and 140, normally closed contacts controlled byarmatures 215 and 216, upper and lower windings of the line relay 202,of the present connector, to battery and ground, respectively.

The line relay 202 energizes over the calling line loop, removes theshunt around the upper winding of the release relay 203 at the Releaserearmature 222 and its front contact it closes a circuit including bothof its windings and the upper winding of the series relay 204. However,due to the fact that the high resistance upper winding of the releaserelay 203 is in series with the upper winding of series relay 204 overone circuit and in series with the lower winding of series relay 204over the other circuit, relay 204 does not energize.

As a further result of its operation, release relay 203 opens a point inthe circuit of the release magnet 210 at armature 219 and its restingcontact, prepares the impulsing circuit at armature 223 and its frontcontact, and places ground potential on the release conductor 139 at'armature 220 and its front contact, to maintain the preceding switchesin their operated positions and also to busy the connector to all otherselectors having access thereto. The connector is now prepared fordialling.

The calling subscriber now manipulates the calling device in accordancewith the second digit in the telephone number. lhen the second digit isdialled, which in this case is assumed to be the digit 1, the circuit ofthe line relay 202 is opened once by the operation of the calling deviceat the calling subscribers substation. When the line rela-y 202 fallsback it places a short circuit around the upper winding of release relay203 at the normally closed contacts controlled by armature 217, and bythe same action it completes a circuit for the upper winding of seriesrelay 204 in series with the lower winding of release relay 203 asfollows: from ground, normally closed contacts controlled by armature217, armature 222 and its front contact, upper winding of series relay204, lower winding of release relay 203, to battery. Due to the factthat the high resistance upper winding of release relay 203 is shuntedout in this circuit the series relay 204 energizes. The current flowthrough the lower winding vof release relay 203 is insuflcient to keept-he relay energized; however, together with the shunt around the upperwinding, the relay is made slow-to-release. The release relay 203,therefore, remains energized.

It may be well to discuss briefly at this time the operation of the linerelay 202 in response. to a series of impulses. Each time line relay 202energizes following the first deenergization, a circuit is closed againfor both windings of release relay 203 in series with the upper windingof series relay 204, and for both windings of release 203 in series withthe lower winding of series relay 204. Re-

lease relay 203 is fully energized again over this circuit. but thecurrent flow over-both windings of series relay 204 is lnsufeient tokeep the relayv energized, however, lenough current Hows to make therelay slow-to-release. The series relay 204, therefore, remams energizedduring each series of nnpulses, but subsequently deenergizes after theline relay comes to rest in its energized position between each seriesof impulses.

When the line relay 202 falls back responsive to the second digit 1, itclosesv a circuit from ground, armature 218 and its resting contact,armature 223 and its front Contact, armatures 241, 274, 249, and 230 andtheir respective resting contacts, contacts 235 of the verticalotr-normal springs VON, armature 236 andy its resting contact, lowerwinding of two-stepV relay 206, to battery. Two-step relay 206 energizesover this circuit in its first step, closinU contacts A only, topreparea locking circuit for both of its win-dings in series, from ground atarmature 221 and its front contact. It is obvious that theupper windingof two-steprelay 206 is short circuited by its initial energizingcircuitover its lower winding and cannot operate to its second step until theshort circuit is removed. The line relay 202 subsequently energizesagain as has been described hereinbeore, and

opens the initial energizing circuit for twostep relay 206 at armature218 and its resting Contact. The opening of the original energizingcircuit for the lower winding of two-step rela-y 206 removes the shortcircuit from its upper winding, permitting the rel to energize to itssecond step over a circuit including both windings in series. All theremaining armatures ot the relay are operated when the circuit iscompleted to both the windings in series. Upon energizing Vto its secondstep, relay 206 prepares a circuit for the combination switch-over andring-cutoff relay 205 at armature 233 and its front contact, it preparesa circuit for the combination discriminating and line reversing relay209 at armature 236 and its front contact, and it prepares a lockingcircuit for relay 209 at armature 237 and its front contact. However,relay 209 is not energized at this time because the calling subscriberhas only transmitted one impulse.

It has been mentioned before that the series relay 204 remains energizedduring a series of impulses. It will be noted that at arm..- ture 268and its front contact an energizing circuit is completed forslow-to-release relay 275. The operation of the slow-to-release relay275 is of no importance at this time. however. the functionk of therelay will be described hereinafter'.

After the first series ot impulses has been transmitted, which in thiscase was only one impulse, line relay 202 remains in an energizedposition. Therefore, the series relay 204 subsequently releases as hasbeen herein-V before described. Upon falling back, series relay 204completes a circuit for the slowacting combination switch-over and ri.ng-cutoif relay 205. by way of ground,armature 226 and its restingcontact. contacts 227 of the vertical off-normal springs VON, armature233v and its front contact, lower winding of relay 205, to battery.Uponl energizing, relay 205 prepares a locking circuit for itself atarmature 229 and its frontcontact andrit prepares a circuit for thevertical magnet 211 at armature 230 and its front contact. The closingof armatures 228 and 231 and -their respective front contacts has noeEect at this time.

The calling subscriber may now dial the third digit of the callednumber, which in this case is assumed to be the digit 3. The circuit ofthe line relayl 202 is again inter- I mittently interrupted `in responsetothe operation of the calling device by the calling subscriber... Theiirst `time the line relay 202 `falls back, series relay 204 energizesand' remains in the energized position throughout vthe series ofimpulses as has been hereinbefore. described. The operationof the seriesrelay 204 opens the initial energizing circuit for the slow-actingcombination switch-over and ring-cut-oif relay 205 at armature 226andits resting contact.l However, it also completes a locking circuit forrelay 205 before it falls back, the locking circuit extending fromground, armature 226 and its front contact, armature 229 and'its iro-ntcontact, lower winding of relay 205, to battery. As-afurther result ofthe fallingback of line relay 202 a circuit is completed for the`vertical magnet 211, from ground, armature 218 and its'resting contact,armature 223 and its front contact, armatures 241, 274, and 249 andtheir respective resting contacts, armature 230 and its yfront Contact,winding of vvertical magnet 211, to battery. Each time the line relay202 falls back this circuit is completed for the vvertical magnet 211and by its operation wipers 257-260, inclusive, vare raised opposite thethirdlevel of the bank contacts.

At the end of the series of impulses for controlling the verticalmovement, the line relay remains energized and series relay 204 shortlyreleases as has been described. The falling back oi series relay 204opens the locking circuit for the combination switch-over andring-cut-off relay 205 at armature 226 and its kfront contact. Relay 205then releases `due to the fact that its initial-energizing circuit has'been opened, bythe rstvertical step of the switch, at contacts 227 ofthe vertical off-normal springs VON. The

circuit for the rotary magnet 212 is prepared at armature 230anditsresting contact by the falling back of relay 205.

The calling subscriber now transmits the final digit of the callednumber, which in this case is the digit 1. VResponsive to the operationof the line relay 202, the series relay 204 is energized again andremains energized throughout the series of impulses. Each time linerelay- 202 falls back a circuit is completed for the rotary magnet 212from ground, armature 218 and its resting contact, armature 223 and itsfront contact, armatures 241, 274, 249, and 230, and their respectiveresting contacts, contacts 234 of vertical ofi-normal springs VON(closed on the first vertical step of the switch), winding of the rotarymagnet 212 to battery. By the operation of the rotary magnet 212, thewipers 257-260, inclusive, are rotated into engagement with the firstset of bank contacts on the third level.

The wipers of the connector have now come into engagement with the firstline of the desired group. The drawing shows only one line connected,that is, the line 261-263 extending to substation A1. It should benoted, however, that all the lines on this level are the same as theline shown. The straps indicated by the reference X, which are jumperedbetween the corresponding contacts inV the banks accessible over wipers258 and 259, are only placed on the contacts of lines that are listedunder one telephone number. It should be noted, however, that the lastline in a. group of lines must not be strapped as shown, as theconnector necessarily must stop on this line whether all the lines inthe group are busy or not. If all the lines of a group are busy theconnector will operate as a regular connector on this line and will givebusy tone to the calling subscriber to indicate that all the lineslisted under the one telephone number are busy. i

It will be. assumed, that the rst line of the group is busy, that is,the test conductor, which is similar to test conductor 262, has beengrounded by another connector or by the individual lineswitch associatedwith the first line. When the test wiper 258 encounters ground on thetest contact, relay 207 is energized over the following circuit:battery, winding of busy relay 207, resistance 232, armature 246 and itsresting Contact, arma.- ture 225 and its front contact (relay 27 5 beingslow-to-release does not tall back immediately), normally closedcontacts controlled by armatures 239 and 245, respectively, test wiper258 to the grounded test conductor similar to conductor 262. Relay 207operates in its first step and operates only armature 240. Relay 207does not operate in its second step at this time because the lockingcircuit including contacts A and armature 240 is opened at the normallyclosed contacts controlled by armature 225. 1t should be noted that theslow-to-release relay 275 is energized over a circuit from battery,winding of relay 27 5, armature 268 and its front Contact, armature 272and its resting Contact,

\ armature 247 and its resting contact, armaseries of impulses, acircuit isl completed for the rotary stepping relay 276 of the connectoras follows: grounded test conductor similar to conductor 262, jumper X,bank contact associated with wiper 259, rotary test wiper 259, armature267 and its resting contact, armature 271 and its front contact, (relay275 being slow-to-release does not fall back when its circuit is openedat armature 268 and its front contact), armature 253 and its restingcontact, self-interrupting springs 269 of the rotary magnet 212, windingof rotary stepping relay 276, to battery. Upon energizing stepping relay276 completes a locking circuit for itself as follows: battery, windingor' relay 276, self-interrupting contacts 269 of the rotary magnet 212,armature 273 and its `rontcontact, armature 247 and its resting contact,armature 221 and its front Contact, to ground. Stepping' relay 27 6 alsocompletes a new holding circuit for the slowto-release relay 275 and anenergizing circuit for the rotary magnet 212, the circuit extending asfollows: ground, armature 221 and its front Contact, armature 247 andits resting contact, armature 274 and its front contact, armature 249and its resting contact to junction 277 whence one branch extends viaarmature 268 and its resting contact, winding of slow-to-release relay275 to battery, and the other branch extends by way of armature 230 andits resting contact, contact 234 of the vertical ott-normal springs VON,windingof rotary magnet 212, to battery. The slow-torelease relay 275remains in its energized position over this circuit and the rotarymagnet 212 energizes. r:The rotary magnet up on energizing advances its-wipers 257426() to the next set of bank Contacts,and at its interruptercontacts 269, opens the circuit for the stepping relay 276. Upon fallingback, the stepping relay 276 opens the energizing circuit for the rotarymagnet 212 and the slow-torelease relay 275 at armature 274 and itsfront contact, and at armature 273 and its front Contact opens itslocking circuit. It the next bank contact encountered by rotary testwiper 259 is grounded by way of strap X and test conductor 262, steppingrelay 276 will be energized over the previously traced circuit. Theoperation of the stepping relay 27 6 completes a locking circuit foritself at armature 273 and its front contact, and at armature 274 andits front Contact completes the holding circuit for the slow-to-releaserelay 275 and the energizing circuit for the rotary magnet 212,-as hasbeen described hereinbefore. The alternate operation of the steppingrelay 27 6 and the rotary magnet 212 continues, if all the intermediatelines of the group are busy, until the last line of the group isreached.

The last line of the group does not have the strap X between the testcontacts accessible to test wipers 258 and the test contacts asso-:relay 208 energizes and at its lightly ad-v ciated with the rotary testwiper 259. Therefore, if the last line of the group is also busy therotary test wiper 259 does not encounter the busy ground. Therefore,stepping relay 276 is not energized to complete the holding circuit forthe slow-to-release relay 275 and the energizing circuit of the rotarymagnet. The ground encountered by the test wiper 258, however, maintainsthe previously traced circuit for energizing the busy test relay 207 inits iirst step. The sloweto-release relay 275 subsequently falls backand at the normally closed contacts controlled by armature 225 itcompletes a circuit for energizing the busy test relay 207 to its secondstep, by way of the grounded test wiper 258, normally closed contactscontrolled by armatures 245, 239, and 225, respectively, armature 240and its front contact A, winding of relay 207, to battery. Uponenergizing to its second step the busy test relay 207 opens a point inthe circuit for the rotary magnet 212 at armature, 241 and its frontcontact to prevent furtlier rotation of the wipers, if the callingsubscriber should inadvertently move his calling device, and at armature239 and its front Contact it transfers the locking circuit for itselffrom ground on the test contact to which wiper 258 has been rotated, tothe ground at armature 220 and its front contact. 'At armature 238 andits front Contact relay 207 connects the busy tone conductor from thebusyvtone machine to the upper side of the line. The calling subscriber,upon hearing the busy signal, will release his receiver therebyreleasing the connector and all previously operated switches.

Referring back now to where the wipers 257-260 were rotatedautomatically from the first to the second set of bank contacts of thethird level it will be assumed at this time that the second line of thegroup is idle.v Under these circumstances the rotary test wiper 259 andthe test wiper 258 will not encounter ground and consequently thestepping relay 276 will fail to energize again and the busy test 'relay207 will fall back. c Therefore, the

slow-release relay 275 will subsequently fallV back and complete thecircuit for the slowactingswitching reay 208 over a circuit as follows:ground, armature 220 and its front contact, armature 239 and its restingcontact,

lower winding of the switching relay 208, armature V240 and its restingContact, normally closed contacts controlled by armatures 225, 239, and245, test wiper 258, test conductor 262, and thence to battery by way ofthe bridge-cut-oif winding-of the associated lineswitch (not shown).Responsive to the closure of this circuit the bridge-cutoff armature ofthe lineswitch is operated to disconnect the line relay of thelineswitch from across the line conductors.

In the connector the slow-acting switching justed armature 247 closes alocking circuit for its upper winding, opens another point in thecircuitv for the rotary magnet 212 at armature 249 and its restingcontact, opens its initial energizing circuit atthe normally closedcontacts controlled by armature 245, and by the same action placesground di? rectly on the test wiper'` 258 and test conductor 262 atarmature 245 and its front contact. The switching relay 208 alsoprepares a locking circuit for the combination switch-y over andring-cut-OE relay 205 at armature 248 and its front contact, connectstheringback-tone conductor to the upper line conductor at armature 242and its front contact to indicate to the calling subscriber that thecalled line is being signalled. Furthermore, this relay connects up theline wipers 259 and 260 at armatures 243 and 251 and their respectivefront contacts. By the latter operation a signalling circuit isestablished whereby ringing current from the generator GEN isintermittently projected "over the line to operate the ringer at stationA1 over the following circuit: battery connected generator GEN,interrupter contacts of the ringing interrupter, armature 231 and itsresting contact, armature 251 and its front contact,

armature 255 kand its resting contact, wiperv 260, line `conductor 261,to the ringer at substationAl. The return path for the ringing currentincludesthe upper winding of the combination switch-over andring-cut-oi' relay 205 and the battery.

When the call ,is answered, by the removal of the receiver at substationA1, a direct current bridge is closed across the associated lineconductors 261 and 263v in the regular manner, whereupon thering-cut-off relay 205 energizes. Y

Upon energizing, the combination switchover and ring-cutoff' relay 205vcloses a lock-v ing circuit for itself at its lightly adjusted armature229, disconnects the line wipers 257 Y and 260 Vfrom its own upperwinding and the generator lead at armatures 228 and 231 andy vtheirrespective resting contacts, and at the same time it opens thering-back-tone circuit to the calling subscriber at the normally closedcontacts controlled by armature 228. At armatures 228 and 231 and theirrespective front contacts theV ring-cut-off relay 205 completes thetalking connection.

Current is `now supplied to the transmitter at substation A1 through thewindings of the doublefwound back-bridge relay V201,

which is accordingly energized. Therelay is a reversing relayand has thewell known function of reversing the' incoming trunk conductors 138 and140, as regards to their connection witlithe windings of linerelay 202.Relay 201 opens a point in the circuit for the release magnet210 atarmature 213 and its resting contact, and at armature 214and its frontAcontact closes an additional holdingV f two circuit for relays 20.6 and208. The reversing of the line conductors 138 and 140 is a standardoperation, and is forl the purpose of oper.- ating a subscriberspaystation or metering apparatus, and in some cases vis used Jforsupervisory purposes. The desired connection is now completed and thesubscribers may converse as desired. Y

When the conversation is completed the subscribers replace theirreceivers. Should the calling subscriber restore hisA receiver irst, theline relay 202 will deenergize and 0 en the circuit of the slow-releaserelay 203. clay 203 subsequently deenergizes and removes the ground fromconductor 139 at armature 220 and its front Contact, releasing thepreceding switches in the usual manner. The connector shown On thedrawing, however, does not release due to the fact that the circuit `forvthe release magnet 210 is opened at arinatme 213 and its rest-ingcontact, and it cannot be seized by any Select-or, because the batterypotential is disconnectedfrom conductor 1 39 at armature 244 and itsresting contact. When the called subscriber at sub.- station A1 hangs uphis receiver, relay 201 de'energizes, removes the locking ground forrelays 2,06 and `208 at armature 21.4 and its front contact, and closesal circuit for there- `lease magnet 210 at armatures 21,3 and itsresting cont-act. The operation ofthe release magnet 210 causes theswitch s haftto restore to normal. l Then the switch shaft has beenfully restored to normal the circuit for the release magnet 210 isopenedl at the contact 224 of the vertical off-normal hsprings VON. Therelease of relay 206 has no effect at this time. `Upon subsequentlyrestoring to normal, the switch-.through relay 208 removes `.5 thelocking ground for the combination switch-.over and ring-cut-off relay205 at armature 248 and its front Contact, removes the groundpotentialrom the test wiper 258 at armature 245 and its front contact,opens the speaking connection at armatures 243 and 251 and theirrespective front contacts, and connects battery to conductor 139 atarmature 244 and its resting contact. It the called par-ty hangs upfirst the connector is then released under control of the callingparty.V

Having described the operation of the switch as a regular rotaryconnector it will now be assumed'thatl the calling subscriber desires toestablish aY connection with a particular one of the lines in a group.The same group of lines will be considered as before, and it will beassumed that the irst line is wanted. A

Itwillbe assumed that the connector shown on the drawing has been seizedover con-.

ductors 13S-140 in the same manner as has been hereinbefore described.In response to the seizing of the connector over line con-v ductors13S-140 the'line relay 202 energizes and causes the releaseV relay 203to energize as before. The energization of the release relay 203 returnsground over release con device b the callino' subscriber line rela Y a a202 falls back and completes a circuit forA the series relay 204 whichremains energized during impulsing. Upon falling back, line relay 202completes a circuit from ground, armature 218 and its resting contact,armature 223 and its front contact, armatures 241, 274, 249, and 230 andtheir respective resting contacts, contacts 235 of the verticaloff-normal springs VON, armature 236 and its resting contact, lowerwinding of two-step relay 206 to battery. Two-step relay 206 energizesin its iirst step, closing its locking contact. `When the line relayenergizes, relay 206 operates fully to close all its contacts. Thesecond time the line relay 202 falls back the impulsing circuitiscompleted over the above traced circuit, but this time includingarmature 236 and its front contact (two-step relay 206 having beenenergized by the first impulse) normally closedv contacts controlled byarmature 254, winding of relay 209 tobattery.

fin

Upon energizing relay 209 immediately loclrs itself, from battery,winding of relay 209, armature 254 and its front contact, armature 237and its front contact, to ground.

It is obvious thattwo-step relay 206 is energized and locked up when thefirst digit dialled to the connector is the digit 1 and that both thetwo-step relay 206 and relay 209 are energized and locked when the firstdigit dialled is the digit 2.

Upon energizing, relay 209 opens the' circuit for the rotary'steppingrelay 270 at armature 253 and its resting contact to prevent theautomatic rotary action of the connector, after the last digit isdialled, when the rotary test wiper 259 encounters a grounded contact.At armatures 252 and 255 and their respective front contacts, relay 209also causes a reversal in the line conductors which is of no importanceat this time.

After the first series of impulses have been transmitted, line relay 202remains in its energized position. Therefore, the series relay 204subsequently releases as has been. hereinbefore described. Upon fallingback, series relay 204 completes a circuit for the slowactingcombination switch-over and ring-cutoff relay 205 from ground, armature226 and its resting contact, contact 227v of the vertical o-normalsprings VON, armature Y Qanditsfront Contact, lower winding of e relay20.5,@ battery. Upon energizing, re`- lay 205 prepares a locking circuitfor itself at armature 229 and its front contact and it prepares acircuit for the vertical magnet 211 at armature 230 and its frontcontact. rllhe operation of armatures 228 and 231 has no ellect at thistime.

The calling subscriber may noW dial the hird digit of the called number,which in this case is assumed to be the digit 3. The operation of theconnector in response to the dialling of the digit 3 causes the linerelay 202 to transmit impulses for operating the vertical magnet 211. Itwill suce to say that by the operation of the vertical magnet 211 theWipers 257260, inclusive, are raised opposite the third level of thebank contracts.

At the end of the series of impulses controlling the vertical movement,the line relay remains energized and the series relay 204 subsequentlyfalls back. The falling back of series relay 204 opens the lockingcircuit for the combination switch-over and ring-cut- OE relay 205 atarmature 226 and its front contact. Relay 205 subsequently releases dueto the fact that its initial energizing circuit has been opened, by thefirst vertical step of the switch, at armature 227 of the verticaloff-normal springs VON. The circuit for the rotary magnet 212 isprepared at armature 230 and its resting contact by the falling bacl: ofrelay 205. The calling subscriber nov: transmits the linal digit of thecalled number, which in this case is the digit 1. Responsive to theinterruption of the line relay 202, series relay 204 is energized againand remains energized throughout the series of impulses. Then the linerelay 202 falls back a circuit is completed to the rotary magnet 212from ground, armature 218 and its resting contact, armature 223 and itsfront Contact, armatures 241, 274, 249 and 230 and their respect-ireresting contacts, contacts 234 of the vertical off-normal springs VON(closed on the lirst vertical step of the switch) Winding of the rotarymagnet 212 to battery. By the operation ofthe rotary magnet- 212, theWipers 257-260, inclusive, are rotated into engagement with the firstset of bank contacts.

The Wipers of the connector have now come into engagement with theWanted line. lt will be assumed that the desired line is busy. lfllhenthe test Wiper 258 encounters ground on the test contact, a circuit iscompleted for the busy test relay 207.

lt shoull be noted that during dialling of the last digit the operationof the series relay 204 completes a circuit for the sloW-to-releaserelay 275 from battery, Winding of slovv-torelease relay 275, armature268 and its front Contact, armature 272 and its resting contact,armature 247 andv its resting contact, armature 221 and its frontcontact, to ground. After the series of impulses have been comla f 27 5bein@ sloW-to-release does not fallback immediately), normally closedcontacts controlled by armatures 239 and 245, respectively, Wiper 258,to the grounded test conductor similar toconductor 262. Relay 207operates in its first step and operates only armature 240. rl'lie rotarytest Wiper 259 also encounters lground on its bank contact which isconnected to the samel bank contact to which test Wiper 258 is engagedwith, by;y

means of thestrap X. In the previous connection the rot-ary steppingrelay 27 6 energi When the rotary test Wiper 259 encounters ground andcauses the rotary magnet 212 to rotate the Wipers to Jthe next set ofbanlrcontacts.v ln establishing the present connection this circuit isopened by the operation of relay 209 at armature 253 and its restingContact. Consefpaently there Will be no automatic rotation of the WipersWhen a busy line is reached.

The sloW-to-release relay 275 subsequently falls back and at thevnormally closed contacts controlled by armature 225 it completes acircuit for energizing the busy test relay 207 I to its secondv step, byWay of the grounded test Wiper 258, normally closed contacts controlledby armatures 245, 239, and 225, respectively, armature 240 .and itsfront contact A, Winding of busy test relay 207, to battery. Uponenergizing to its second step the busy test relay 207 opens a point inthev circuit for the rotary magnet 212 at armature 241 and its frontcontact to prevent further rotation of the Wipers, should the callingsubscriber move his calling device, and

at armature 239 and its front Contact it trans-r fers the lockingcircuit for itself from ground on the test conductor to which Wiper 258has been rotated, to the ground at armature 220 and its front contact.At armature 238 and its front contact, relay 207 connects the busytoneconductor from the busy-tone machine to the upper side of the line. Thecalling subscriber, upon hearing the busy signahvvill replace hisreceiver, thereby vreleasing the connector and all previously operatedswitches.

Assuming now that the called line is idle when the connection isestablished. Under these circumstances the test Wiper 258 will notencounter ground and consequently the busy test relay 207 Will noti beenergized. The sloW-to-release relay 275 subsequently falls back andcompletes the circuit for the slow-acting switching relay 208 over acir- -ringer at the wanted subscribers station.

'from its own upper winding and the line cuit as follows ground,armature 220 and its front contact, armature 230 and its restingcontact, lower winding of switching relay 208, armature 240 and itsresting contact, normally closed contacts controlled by armatures 225,239, and 245, test wiper 258, test conductor (similar to the testconductor 262), and thence to battery by way of the bridgecut-orilwinding of the associated lineswitch (not shown). Responsive to theclosure of this circuit the bridge-cut-of armature of the lineswitch isoperated to disconnect the line relay of the lineswit-ch from across theline conductor.

In the connector the slow-acting switching relay 208 energizes and atits lightly adjusted armature 247 closes a looking circuit tor its upperwinding, opens another point in the circuit for its rotary magnet 212 atarmature 249 and its resting contact, opens its initial energizingcircuit at the normally closed contacts controlled by armature 245, andby the same action places ground directly on the test wiper 258 and thetest conductor (similar to test conductor 262) at armature 245 and itsfront contact. The srv/itching relay 208 also prepares a locking circuitfor the combination switchover and ring-cut-ol relay 205 at armature 248and its front contact, connects the ring-back-tone conductor to theupper line conductor at armature 242 and its front contact to indicateto the calling subscriber that the called line is being signalled, andit connects up the line wipers 257 and 260 at armatures 243 and 251 andtheir respective front contacts. By the latter operation a signallingcircuit is established whereby ringing current from the generator GEN isintermittently projected over the line to Operate the The return pathfor the ringer current includes the upper winding of the combinationswitchover and ring-cut-oiiz relay 205 and th-e battery.

'Vhen the call is answered, by the removal of the receiver at the calledsubstation, a direct current bridge is closed across the associated lineconductors in the regular manner, whereupon the ring-cut-oi' relay 205energizes.

Upon energizing, the combination switchover and ring-cut-oti. relay 205closes a locking circuit for itself at its lightly adjusted armature229, disconnects the line wiper 260 wiper 257 from the generatorconductor at armatures 228 and 231 and their respective restingcontacts, and at the same time it opens the ring-back-tone circuit tothe calling subscriber at the normally closed contacts controlled byarmature 228. At armatures 228 and 231 and their respective frontcontacts the ring-cut-off relay 205, completes the talking connection.

Current is nowl supplied to the transmitter'v at the wanted subscriber-sstation Vthrough the windings of the double-wound backbridge relay 201,which is, accordingly, energized. This relay is a reversing relay andhas the well known functions of reversing the incoming line conductors138 and 140, as regards to their connection with the windings of theline relay 202. Relay 201 opens a point in the circuit for the releasemagnet 210 at armature 213 4and its resting contact, and at armature 214and its front Contact it closes an additional holding circuit for relays206 and 208. The reversing of the line conductors 138 and 140 is astandard operation, and is for the purpose of operating a subscriberspaystation or metering apparatus, and in some cases is used forsupervisory purposes. The desired connection is now completed and thesubscribers may converse as desired.

`When the conversation is completed the two subscribers replace theirreceivers. A detailed description of the circuit operations during therelease of the connector shown on the drawing has been givenhereinbefore and it will su'iiice to say that the switch is restored toits normal position when the two subscribers replace their receivers.

lt is evident now that the connector can be used to select the firstidle line in a group of lines which are all listed under one telephonenumber, or may be operated as a regular connector to establish aconnection with any particular line in a group of lines listed under onenumber. This feature is particularly desirable in the case of nightlisting of telephones when only certain oi' the'lines, in a group oflines listed under one number are available for connection afterbusiness hours.

A detailed description of the opera-tion which takes place when acalling subscriber desires to establish a connection with the party-linesubscriber B1 Whose telephone number is 3121 will now be given. Then thecalling subscriber removes his receiver and dials the digit 3 theoperation of the Vlineswitch and the selector is exactly the same asbefore. The selector is positioned to the third level of the selectorbanks to engage the bank contacts to which conductors 138--140 inclusiveare connected.

In response to the seizing of the connector, in the present case, overline conductors 138 and 140, the line relay 202 and the release relay203 are energized and the connector is prepared to receive the seconddigit of the telephone number, which in this case is the digit 1. It hasbeen mentioned above that when the iirst digit dialled into theconnector is the digit 1 the two-step relay 206 is energized and lockedup over both its winding in series to ground at armature 221 and itsfront contact.

In response to the third digit of the telethe digit 1. In response tothedialling of the digit 1, line relay 202 is momentarily derelease relayv275 falls back and completes the circuit for energizing the busy testrelay` e 207 in its second step, by this action relay`207 transfers thelockin circuit for itself from' the grounded test Wiper 258 to ground atarmature 220 and its front contact. The calling subscriber now receivesa busy-tone signal from the busy-tone machine indicating that thevwanted subscribers line is busy. Upon hearing the busy signal thecalling subscriber will hang up his receiver, thereby releasing theentire connection.

It will be assumed that when the wipers 257-260 are rotated intoengagement with the wanted subscribers line, to which conductors 264-266are connected that the line is idle, therefore, no ground isVencountered by the test wiper 258. Therefore, the busy-test relay 207is not energized. As soon as the slow-to-release relay 275 falls back acircuit is completed for the slow-acting switching relay 208 as followsground, armature 220 and its front contact, armature 239 and its restingcontact, lower Winding of switching relay 208, armature 240 and itsresting contact, normally closed contacts controlled by armatures 225,239, and 245, test wiper 258,`test conduc-y tor 265, thence to batteryby way of the bridge-cut-o winding ofthe associated lineswitch `(notshown). Responsive to the closure of this circuit the bridge-cut-oifarmature of the lineswitch is operated to disconnect the line relay ofthe lin'eswitch from across the line conductors. Y

In the connector the slow-acting switching relay 208 energizes and atits lightly adjusted armature 247 closes a locking circuit for its upperwinding, opens another point for the circuit for the rotary magnet 212at armature 249 and its resting contact, opens' its initial energizingcircuit at the normallyv closed contacts controlled by armature 245, andby the saine action places ground directly on the4` test wiper 258, andtest conductor 265 at ar-y mature 245 and its front contact. Theswitching relay 208 also prepares a locking circuit for the combinationswitch-over and ring-,cut-

off relay 205 at armature 248 and its front contact, connectsring-back-tone conductor tothe upperlline conductor at armature 242 andits front contact, to indicate to the calling sub.-A scriber that thecalled line is being signalled, andit connects up the line wipers 257and 260 at armatures 243 and 251 and their respective front contacts. Bythe latter operationA ai signalling circuit is established wherebyringing current from the generator GEN is Vintermittently projected overthe line to operater the ringer Vat substation B1 over the kfollowingcircuit: battery connected generator GLN, interrupter contacts of theyringing interrupter, armature 231 and its resting contact, armature 251andits" front contact, ar

mature 255 audits resting contact, Wiper 260, line conductor"264,ringerat substation B1, to ground. y,The above circuit is intermit1'r tentlyopened and closed by the operation of the ringing interrupter and theringer at substation B1 is thus operated at inter# vals to signal thecalled subscriber. WhenV the called subscriber at substation B1 removesvhis receiver to-answer the call,`the ringer thereat is disconnected anda direct current circuit is completed over the otherv line conductor26,6,1wiper 257, armatureY 252 and-its resting` contact, armature l243and its-front contact, armature 228 and its, resting contact, upperwinding of the ringcutotf relay 205', to ground'.- Hrlhe combinationswitch-over and ring-cutoff relay 205 energizes over this circuit andcloses a loc-king circuit for itself at its lightly'adjustedarmature229and its front Contact, from ground at armature 248 and itsfront contact,through the lower wind-A ing of relay 205`7to battery.Relay 205 Aalso opens its initial energizing circuit at arma'- tures 228and l2,81`a-nd their respective resting contacts, 'completes a talkingconnection at their respective front contacts, and bythe same actionldisconnects the ring-back-tone conductor from the upperA line conductor188;A

Current is now supplied tothe transmitter at substation B1 through theWinding of the double-wound back-bridge relay 201, which is accordinglyenergized. The functions ofv group which are listed under one telephone,

number. If, however, a Vcondition, should' leq lao

arise wherein it would be necessary to use the second level for a groupof lines, straps or jumpers similar to strap X are all that are requiredto change the operation of the connector from a regular connector to arotary connector.

It will now be assumed that the calling subscriber desires to establisha connection with the subscriber at substation B2, whose telephonenumber is 3221. The setting up of thev connection is exactly the same asdescribed inv establishing a connection with the subscriber atsubstation B1, whose telephone numbery is 3121, except that the seconddigit dialled is a 2 instead of a 1. The first digit 2 dialled into theconnector (the second digit of the telephone number), locks up thetwo-step relay 206 as before, in addition completes an energizingcircuit for relay 209 which accordingly energizes and locks itself atarmature 254 and its front contact. The connection is then completed aspreviously described, but in this case the ringing current istransmitted by way of armature 255 and its front contact, line wiper257, line conductor 266, through the ringer and ground at substation B2.It should be notedvthat the operation of relay 209 causes the ringingcurrent to be transmitted over the op-posite line conductorfrom thatused lin signalling the subscriber at substation B1.

Vhen the subscriber at B2 responds to the ringing of his bell byremoving his receiver 3 a direct current circuit is completed over theother line conductor 264, lin-e wiper 260, ar-

mature 252 and its front contact, to the upper winding of thering-cut-oif relay 205.

The ring-cut-oif relay 205 is energized over this circuit as before andthe talking connection is completed. The release of the connector hasbeen described hereinbefore and it will suffice to say that theconnector is released under control ofthe last party to f hang up.

The operation of the connector to establish a connection with individualline subscribers is :exactly the sameas has been described in connectionwith establishing a connection with the subscriber at substation B.

by the jumper X and with only four v, lines in Vthis particular groupthe fourth set of bank contacts accessible to wipers 258 and 259 is notstrapped. The tel-ephone number of the group of lines in this case is3131. If all thelines' in the group are busy the connector willautomatically rotate its wipers to the fourth set of bank contacts andif that line is also busy will return busy tone to the callingsubscriber. other group of lines may be wired on theremaining set ofbank contacts on the third level, that is, the fifth, sixth, seventh,eighth, ninth, and tenth sets of bank contacts of the level, the Xjumpers being wired between the bank contacts associated with wipers 258and 259 on the fifth to the ninth sets of bank contacts, inclusive.However', the tenth set of bank contacts will not be jumpered by meansof the strap X. The telephone number listed in the directory for thegroup of lines in this case will be 3135. In response to the last digitdialled, which is the digit 5, the rotary magT net will be controlled byimpulses from the line relay to rotate the wipers 257-260 of the' switchto the fifth set of bank contacts on the third level.l After the impulseseries, the series relay 204 subsequently falls back and prepares therotary test circuitto the rotary stepping relay 276. Then, if the rotarytest wiper 259 Vencounters ground on the fifth set of bank contacts byway of the jumper Xand X, the rotary test wiper 259 is not grounded.

I-Iowever, the regular test wiper 258 encounters the grounded bankcontact and lousyA tone is transmitted to the calling subscriber.

Eo indicate that all the lines in the group are usy. v

What is claimed is:

1. In an automatic telephone system, a connector switch, a group oflines accessible. to said switch, means responsive to a predeterf minedfirst digit for preparing said switch to operate as a regular connectorto select` anyl particular line in said groupof lines, and meansresponsive to a ldifferent predetermined first digit for preparing saidswitch to Operate as a rotary connector to automatically select thefirst idle linev encountered in said group of lines. Y 2. In a telephonesystem, a connector, a

group of lines, means for directively operat` ing the wipers of saidconnector to engage the rst line in said group of lines, means operatedwhen said first line is busy for automatically rotating said wipers tohunt for An-v iio

an idle line in said group, and means controlled by a calling subscriberbefore the directive operation of said connectoris coinpleted forpreventing said automatic rotation if saidv first line isbusy.

3. In atelephone system, a rotary connector, a group of linesaccessible'to sai-d connector, means for operating said connector in aprimary and secondary movement to select said group of lines, and meansresponsive before said primary and secondary movements for eithercausing said connector to automatically rotate to select the first idleline in said group or for causing said connector to remain connected tothe first line of the selected group regardless of the idle or busycondition of said first line.

4. In a telephone system, a three-digit connector switch, group of linesaccessible to said switch, means for operating a pair of relaysresponsive to impulses indicative of a particular first digit, means foroperating only one of said pair of relays responsive to a differentfirst digit, means responsive to impulses of the second and third digitsfor operating said switch to select said group of lines, and meansincluding said relays for determining whether said switch will hunt foran idle line in the group or not.

5. In a telephone system, a three-digit connector switch, meansresponsive to a first digit dialled by a calling subscriber forpreparing said switch for further operation, a group of lines accessibleto said switch, means responsive to the remaining digits dialled forselecting said group of lines or any particular line in said group,means determined by the value of said first digit for controlling theoperation of said connector after the group of lines or particular linein said group has been selected, and means including said last-mentionedmeans for automatically rotating the wipers of said switch to find anidle line in said group if the first line in the group is busy or forpreventing automatic rotation regardless of the busy or idle conditionof the first line or particular line.

6. In a telephone system, a three-digit connector, a plurality ofcontrol relays, all of which are operated responsive to a first digit ofa predetermined value and one of which is operated responsive to a firstdigit of a predetermined lesser value, the operation of the said one ofsaid relays preparing said connector to respond to the second and thirddigits, a group of lines, means responsive to said second and thirddigits for advancing the wipers of said switch to engage the first lineof said group of lines, means for automatically advancing said wipersifrsaid first line is busy to hunt for the first idle line in saidgroup, and contacts operated when both of said relays are operated forpreventing said automatic advancement of the wipers whether the firstline is busy or idle.

7. In an automatic telephone system, an automatic switch controlled by aplurality of series of impulses transmitted by a calling subscriber, atwo-step relay operated through its first step by the first impulse ofthe first series, contacts on said relay for operating it through itssecond step when said first impulse of said first series is terminated,a second relay operated and locked up responsive to a second impulse-ofsaid first series, a group of lines accessible to said'switch, means forpositioning the wipers of said switch responsive to the second and thirdseries of impulses to select said group, means responsive when the firstline of said group is busy for automatically rotating the wipers of saidswitch to select an idle line in said group, and contacts on said secondrelay for preventing said automatic rotation of the wipers of saidswitch regardless of the busy or idle condition of the first line ofsaid group. Y

8. In a telephone system, a calling linea group of lines, a connectorswitch controllable over thecalling line to select said group of linesamong other lines accessible to said switch, an auxiliary slow-actingrelay, a motor magnet and means for operating the same automatically` tocause said switch to select the first idle line in said group, saidmeans including a stepping relay for sending impulses to said magnet andsaid auxiliary relay, means eective when the last line in said group isencountered for preventing said stepping relay from energizing whethersaid last line is busy or idle, and means responsive to the release ofsaid stepping relay and then said auxiliary slow-acting relay forconnecting said calling line with a source ofbusy signalling current itsaid last line' is busy and for connecting a source of signallingcurrent to signal the party on said last line if said line is idle.

9. In a telephone system, a three-digit connector for establishingconnections with twoparty lines, a group of lines, means responsive whenthe wipers of said connector are engaged with the first line in saidgroup of lines for automatically rotating said wipers to search for anidle line in said group if said first line is busy, means for preventingsaid automatic rotation of the wipers regardless of the busy or idlecondition of the first line in said group, meansv responsive when thewipers of said connector engage a twoparty line for transmittingsignalling current to signal one of the subscribers on said two-partyline, and means including said automatic rotary preventing means fortransmitting the signalling current to signal the other subscriber onsaid two-party line.

10. In an automatic connector switch, a Wiper reversing relay operatedunder control of a calling subscriber, a two-step relay operated undercontrol of a calling subscriber through its first step to close alocking circuit for itself which operates the relay through its secondstep when its initial energizing circuit is opened, contacts on saidrelay for preparing a circuit for said wiper reversing relay, a sourceof current for signalling a wanted subscriber when the connection hasbeen established, said source of current normally applied to one of theline conductors when a connection is established, and contacts on saidWiper reversing relay v for directing said signalling current over the 5other side of the line. s

In Witness whereof, I hereunto subscribe my name this 24th day ofNovember, A. D.

FREDERICK L. KAI-IN.

